Dynamoelectric machine



Nov. 8, 1949 A. c. HUGHN l 2,487,552?,

DYNAMOELECTRIC MACHINE Nov. 8, 1949 A. c. Husum 2,487,551

DYNAMOELEGTRIC MACHINE Filed July 28. 1947 2 Sheets-Sheet 2 WWW PatentedNov. 8, 1949 UNITED STAT ES PAT ENT @FFI-CE DYNAMOELECTRIC MACHINEvAdolph C. Hugin, Arlington, Mass.

Application July 28, 1947, Serial No. 7645182 15 Claims. 1

Myinventionrelatesto dynamoelectric machines and particularly to-eddycurrent inductor type. machines Whichare adaptable for use as clutches,dynamometers, brakes, or similar equipment;

Ari-object of my invention is to provide an improved dynamoelectricymachine of the inductor type.

Another object of my invention is to provide an-inductorr dynamoelectricmachine with animproved cooling system.

A further object of'my invention is to provide anl improveddynamoelectric machine of the inductor typeparticularly adaptable tomass production by the provision of similar units which may be'readilyassembled'in multiple to provide the desired capacity toa machine.

A still further object of my invention is to provide adynamoelectricmachine of the inductor type having an improved magnetic system formorel effectively and eliiciently utilizing the material of which themachine is built.

Further objects and advantages of my invention will become-apparent andmy invention will bebetter understood from the following descriptionreferring to the accompanying drawings, and the features ofV noveltywhich characterize my invention `will be pointed out with particularityin the claims annexed to and forming part of this specification.

In the drawings, Fig. 1 is a side elevational View, partly in section,illustrating an embodiment of my-invention; Fig. 2 is a sectional Viewtaken along line 2--2 of Fig. 1; Fig. 3 is a sectional view takenalongline 3-3- of Fig. 1; Fig. 4fis a sectional -view taken along line 4 4 ofFig. 1; Fig. 51s aside elevational View', partly-in section, of amodication of my invention shown in Figs. 1 to 4 with a part of themachinebroken away; and Fig. 6 is a sectionalview taken along the brokenline 6 6 through an air gap of the machine shown in Fig. 5.

Referring to Figs. 1 to 4 of the drawings, I have shownone embodiment ofmy invention applied to-axdynamoelectr-ic machine-ofthe inductor eddyc-urrent type particularly constructed for use as adynamometer or abrake. In this construction, the dynamoelectric machine is provided withtwo relatively rotatable members, one ofwhich is mountedas-arelativelystationary member and is supportedby end bearing housing frames I and 2whichare` rotatably supported by any suitable bearings., such asantifriction roller. bearings 3 and 4- mounted-in pedestals 5 and 6which form part. of the mainsupporting base 1; of themachine. Thepedestals 5'A and 6 are preferably formed with upperportions whichprovide for the ready assembly and disassembly of the supportingbearings and are, therefore, preferably made as removable bearinghousing caps 8 and g'secured to the lower portions of the pedestals inany suitable manner, as by through bolts extending into ianges l? and IIof the pedestals 5 and 6. The bearings 3 and4 preferably are formedas-double tapered roller bearings to provide for the absorpe tion of endthrust: which may be transmitted thereto by the relatively stationarymember of the machine. In the construction of my improved machineillustratedin the drawings, the end thrust of the machineis adapted'tobe neutralized by the electromagneticV arrangement such that undernormal operating conditions substantially no end` thrust. should betransmitted to the bearings which are arranged to supportV thestationary member of the machine.

The relatively stationary member-of the machine is formed with a pair ofaxially spaced end core members I2 and I3l and may be provided with oneor more intermediate core members asshown at. I4 and I5. in Fig. l.These core members all are formedV of magnetic material withsubstantially radial faces I6 and Ilon the end members I2 and I3, and I8and I9; and 2|] and 2-Iv0n the intermediate members I4 and 153respectively. The stationary core members are arranged to provideV pairsof: axially spacedV radial faces on adjacent stationary: core members,betweeneach pair of which a core member ofthe-main rotatable member isarranged.

When the capacity4 of the machine is.l such that it is desirable toprovide a plurality of pairs of axially spaced stationary core. faces,such as'that shown in Fig. 1, the. main rotatablemember. of the machineis provided with a plurality of simi.- lar core members- 22.: ofmagneticmaterial`r ar,- ranged one intermediate each pair of axiallyspaced radial faces of adjacent: stationary core members.l Theserotatable corsmembers, 22:1 are formed with substantially radialiaces2.3.;on each side thereof which are axially:v spacedifromade jacentstationary core member faces by relatively small air gaps, indicated at;2li. The rotatable core members ZZare rigidly mounted on a suitableshaft 25 and may be secured thereto inany suitable mannenas by. aipressft..

In assembling. the machine, the4 rotatableY core members may besecuredtoitheshaft 25;with-the desired spacing on each side of theintermediate stationary core members., and. ther air gapsfbetween therotatable and stationary membersmay be more accurately adjusted bysecuring together the stationary core members through housing members 2esecured to adjacent stationary core members in axially adjustablerelation by bolts 2l extending through axially elongated openings in thehousing members. This provides for slight axial adjustments of thestationary core members, and, if desired, the air gaps may be checkedthrough suitable peep holes in the housings 26 with suitable removablecovers. Suitable bearings 28, preferably of the antifriction type, aremounted in each of the stationary supporting end frames l and 2 forrotatably supporting the rotatable member shaft 25, and a suitablecoupling 2S may be secured to either or both ends of the shaft forconnection to an external shaft. i

In this type machine, it is desirable that the energy which is to beabsorbed when the machine is utilized as a brake or dynamometer shallrbegenerated as eddy currents in either or both the stationary or rotatablemembers of the machine, and that the heat produced by these eddycurrents be dissipated as quickly as possible to utilize the material inthe machine most eciently and to prevent overheating of the machine.

In the embodiment of my invention illustrated in the drawings, the eddycurrents are adapted to be generated in both the rotatable andstationary members in the larger surfaces of both of these members,thereby utilizing the material of these members to maximum capacity.

The magnetic excitation of the machine may be provided in any suitablemanner, as by electromagnetic iield exciting windings mounted in themachine to provide a substantially torric magnetic field linking thestationary and rotatable core members. The material of the core membersof the machine is most effectively utilized by providing forsubstantially uniform magnetic Y density in the surfaces of the radialcore faces. This may be obtained in my improved construction byproviding a substantially circular field exciting winding recess in eachof the stationary core members and arranging a eld exciting winding inthese winding recesses which is adapted to be electrically energized inany suitable manner. The substantially uniform saturation of the radialcore faces is obtained by arranging the field exciting winding recess insuch a position as to divide the stationary member faces into twosubstantially equal areas radially spaced apart. As shown morespecifically in Fig. 4, this may be done by making the radius r1 of theinner edge of the stationary core members and the radii r2 and r3, whichdenne the inner and outer sides of the winding recess, and

'the radius r4 which determines the outer peripheral edge of thestationary core member, such that the area between the circles drawn atthe radii r1 and r2 is substantially equal to the area between thecircles drawn at the radii r3 and r4; in other words, such thatr42-r32=r22r12.

In order to generate eddy currents in the radial faces of the stationaryand rotatable members,

Ait is necessary that magnetic flux variations or equally angularlyspaced apart, and the number of these slots which are provided may bemade such as to obtain the desired ux density or saturation in the corematerial between the slots which form the magnetic exciting teeth. Thematerial of the machine is adapted to be utilized still more effectivelyby providing a plurality of outwardly extending substantially equallyangularly spaced slots 3i in the radial faces of the rotatable coremembers 22, but the number of these slots is considerably less than theslots in the stationary member, so that a larger amount of the radialfaces of the rotatable core members is available for the generation ofeddy currents therein than in the stationary core member faces, ascooling of the rotatable core members can be more effectively obtainedthan cooling of the stationary core members because of the rotationthereof.

In such an inductor type machine, it is desirable to provide for aslarge as possible a range of smooth torque absorption through as largeas possible a range of speed. This is facilitated by minimizing erraticaction and torque pulsations which may be produced by the forces actingon the stationary and rotatable members of the machine. Any tendency ofthe stationary and rotatable members to lock in any given position wouldtend to produce undesirable torque pulsations, and this is minimized inthe illustrated construction by forming the slots 3| in the rotatablecore members diierent in number from and axially spaced Van unevenmultiple of the annular spacing of the stationary core face slots 3U,such that not more than one of the rotatable member core Yslots 3l canat any time become aligned with a stationary core member slot 36.

The magnetic excitation of the machine may be obtained in any suitablemanner and is preferably provided by a field exciting winding whichincludes a plurality of exciting winding coils arranged in fieldexciting winding recesses in the stationary core members. For the mosteffective use of the radial faces of the stationary core members, theeld exciting winding recesses are formed with inner and outer sides onthe radii r2 and r3, as shown in Fig. 4, and the field exciting wiridingrecesses 32 and 33 in the stationary end core members l2 and i3,respectively, are formed in this manner and are substantiallyring-shaped and of a substantially uniform depth. Similar field excitingwinding recesses and field exciting winding coils are formed in theintermediate stationary core members le and l5 when such intermediatecore members are provided. The maximum eicient capacity of such amachine will be limited by the minimum section of core of thestationaryrcore member due to saturation of the minimum section of suchcore member. The main core section in each case is the portion of thecore directly adjacent the base of the eld exciting winding recesses. Inthe end members i2 and i3, this section may be made of such a dimensionas to provide the desired saturation to the teeth between the slots 3Gwithout saturation Aof the core section behind the base of the windingrecess. The provision of such a depth to the core section between thewinding recesses in the intermediate stationary core members may resultin unduly increasing the depth of these stationary core members andthereby increasing the overall length of the machine. As shown in Fig.1, the overall length of the machine may be decreased'by increasing theeffective section between the field exciting windingl recesseslntheintermediate'` members. T-his is obtained by-forming thel field?exciting winding recesses in both-facesof the intermediateV stationarycore members with substantially circular innerV andouter radially spacedsides 34 and 35 and 36 and- 31"-andwithbases- 3'8\ and 39 which extendannularly totheplane-of the faces of the intermediate core member, suchthat a section through the intermediate core member providessubstantially parallel bases to the two winding recesses with the widersidev 34- of the winding recess 49 nearer they outer periphery of thecore and the wider side 36 of the winding recess 4i nearer the axis ofthe core. This is further improved-by displacingfthe` winding recess 45radially nearer the; outer periphery of the core than the most desirableposition, as indicated by the radii in Fig; lv and the winding recessesin the end core members, and with. the other winding recess 4|v with thewider side 32 thereof nearer the axis of the machine displaced nearerthe axis of the core than the most desirable location, as indicated byFig. 4. This provides a relatively large magnetic material sectionbetween the intermediate core member recesses 4l) and 4l which may bemade with substantially the same winding recess cross-sectional area asthat of the winding recesses in the stationary end core members. Withsuch an arrangement of the intermediate core member recesses, the largernumber of eld exciting Winding coil turns is arranged nearer the smallerface section of each of the faces, thereby minimizing the effect oftheloss due toflux leakage between the turns of the coil and the core.

In order more effectively to utilize the material in this type machine,it is desirable that the heat generated by the eddy currents in thefaces of the stationary and rotatable members be dissipated as rapidlyas possible to provide for maximum absorption of thefenergy transmittedto the machine. This may be effectively obtained by cooling the machinethrough direct contact of the surfaces in which eddy currents aregenerated by a suitable cooling fluid. In addition, cooling fluid may bepassed through the core members and further assist in removing a portionof the heat generated by eddy currents by direct flow through thesemembers. In the construction shown in Figs. 1 through 4; this isobtained by supplying a suitable cooling fluid, such as water, into thestationaryrv member of the machine through a header system includingconnecting pipe sections 42 and 43, towhichY water is supplied throughAa flexible connection 44, such as a rubber hosing, which is. connectedto a suitable source of cooling fluid supply. These connecting pipesections 42 and 43 areV connected to nipples 45 and 46 throughv Ls 41and Ts 48', respectively. The connecting pipe sections 43 are connectedto the flexible connection 44 through a suitable. T 49..andparregulating. valve This valve 50 may be of; the electromagnetictype which is adapated to vary the flow of `cool.- ing fluid inaccordancewith thetemperature of the cooling. fluid which is exhaustedvfrom the machine, such that if this temperature. exceeds a predeterminedmaximum. value, the. electromagnetic valve 50. permits a greater flow ofcooling fluid, and if the exhaust temperature of the cooling fluidfallsv below a` predetermined value, the electromagneticvalve.54tendstorestrict the flowof coolingfluid. The controlicir.- cuitfor thisvalver ymaybe; any suitable ther.- mcstatic control of conventional.arrangement 6. and; therefore, is lnotillustrated inv order notxtocomplicate the drawing with; a well' known fea.- ture. This controlV of'the amountv of. cooling fluidi passing through the machiney assures themost efficient: utilization of; cooling fluid so asto prevent.overheating of the machine and also to prevent a wasteful flow. ofexcess cooling fluid through the machine.

The cooling fluid isadmitted into the-interior of the machine from thesupply nipples 45 and 4E and flows into radially extending. coolingfluid passages 5i and 52 in the end and'intermediate stationary coremembers, respectively. These radially extending cooling fluid passages5.1. and 52 communicate with axially extending cooling fluidz passages53 and 54, through. which the cooling fluid flows into cooling fluidsupply tubes 55 and 55', respectively, securedto the. stationary membercores. The cooling fluid is supplied to the rotatable member cores 22from the tubes iand 5.6 by passing from theseV tubes. into cool.- ingfluid troughs el which extend between inner and outer annular lips 58and 59, and the-troughs 5TA communicate by a plurality of substantiallyequally angularly spaced angularly extending passages SB whichcommunicate with aplurality of outwardly extendingsubstantially radialpas.- sages Si spaced substantiallyA equally angularly around theperiphery of the rotatable member core and extending throughsubstantially the central axial parts of these members. TheF out.-wardly extending cooling fluid passages 5l preferably are arrangedequally. angularly between the slots 3| and communicate with the airgaps between the rotatablev and stationary members through a pluralityof angularly outwardly ex'.- tending passages 62, 63, and 64- on` eachside thereof, such that rotation ofthe rotatable mem.- ber. cores 22causes cooling fluid to be pumped underr centrifugal force through thepassages 6| and to flow outwardly through the passages 62, 63. and 64manvoutward direction into Contact withzthe radial eddy current faces ofthe stationary member cores. In this manner, the cooling fluidis sprayedin a relatively thin film over the entire surfaces of the stationarymember. cores andp'is. also splashed back over the eddy current surfacesofthe rotatable member cores. In addition, the cooling fluid passes overthe outer surfaces of the field excitingv winding coils and thereby alsoremoves the heat generated by the exciting current in these coils.

Rotation of the rotatable member cores imparts tor-the cooling fluid,which is pumped through the cooling fluid passages in these cores, anoutwardly-directed force which causes the cooling fluid to passradiallyoutwardly from the-air gaps between the rotatable and stationary membercores into the space around the rotatable member core on the outside ofthe air gaps within the housing 26. These housings 26 form cooling fluidcollecting scrolls such that cooling fluid passing into these housingswill collect in the lower portion of the machine, from which it isadapted to bedrained. The radially extending cooling fluid passages 6|may be mosteffectively utilized as direct cooling channels byrestricting the openings in the ends of these passages by the insertiontherein of plugs 65 which are each formed with a restricted orificeliliV therethroughto limit the amount of cooling fluid which passesdirectly into the kcollecting housings 26.

In order tofaoilitate the. manufacture of the stationary member. cores,the-cooling fluid passages` 51 and. 52 are adapted tubedrilledicompletely through the core members and the inner ends of thepassages and 52 are adapted to be closed off by suitable threaded pipeplugs 61 and 68, respectively. The cooling fluid passages 53 may bedrilled through from the inner sides of the cores, and the inner ends ofthese passages also may be blocked by suitable threaded pipe plugs |39screwed into the ends thereof.

In this construction, the intermediate stationary core members l i andI5 are rotatably mounted about the rotatable member shaft on suitablebearings, such as antifriction roller bearings I8, preferably of thesealed type, and labyrinth sealing rings '5| are arranged on each sideof these bearings and secured to the stationary member cores to preventthe passage of cooling iiuid into these bearings. Other suitablelabyrinth sealing rings 'i2 are secured by bolts i3 to the end bearinghousing frames I and 2 to prevent the passage of cooling uid into thebearings 28, and these rings also form bearing race retaining membersfor the outer races of the antifriction bearings 28.

The cooling fluid which passes out of the air gaps of the machine intothe collecting troughs formed by the housings 25 collects in the lowerportion of these housings and is adapted to be drained therefrom throughopenings 'i4 formed in the lower sides thereof and through funnelshapeddrains 'i5 secured to the housings 26 over the openings ld. In lorder tominimize hydraulic drag and thereby also minimize any tendency towardserratic action by flooding of the machine, I provide a transverselyextending baille 18 in the lower part of each of the housings 2Barranged over substantially the center of each drain opening 14, suchthat any cooling fluid which tends to circulate around the collectingtrough will impinge against the bailile 76 and be deiiected downwardlyand outwardly through the drain 15. This provides for the absorption ofthe tangential component of force in the cooling fluid and provides forits exhaust radially from the machine, thus providing for an accuratemeasurement of the energy absorbed by the machine. surface l1 of thebaffle I6 is preferably formed with a slight depression near the centerportion directly over the rotatable member core to permit a certainamount of cooling fluid to spill over this portion of the baffle and toprevent a direct hydraulic drag on the rotatable member core. Thecooling fluid which is exhausted through the drains 75 is collected insmall collecting sumps 18 which are connected by suitable drain pipes'I9 to a drain connection 80.

When this type machine is utilized as a dynamometer, weighingV balancearms are adapted to be connected to the stationary member through lugs8|, as in any conventional equipment of this type. In addition, in thistype Inachine, the rotation of the relatively stationary member islimited to a predetermined angular displacement by a suitable set ofstops which may include a stop 82 secured to the end bearing housingframe 2 and a pair of spaced apart Astops 83 mounted on the pedestal 6.

The upper the 'device asa dynamometer in addition toa high efficiencyand effective utilization of the material of the machine.

In Figs. 5 and 6 of the drawings, I have shown another embodiment of myinvention applied to a dynamoelectric machine of the inductor eddycurrent type similar to that shown in Figs. 1 to 4. In thisconstruction, the dynamoelectric machine is provided with two relativelyrotatable members having simplied structural features which can alsoreadily be utilized in a construction such as that shown in Fig. 1.These features particularly include an improved cooling system andimproved mountings which facilitate assembly and repairs of the machine.One of the two relatively rotatable members of the machine is mounted asa main relatively stationary member and is supported by end bearinghousing frames 813 and which are rotatably supported by any suitablebearings, such as antifriction roller bearings 86 mounted in pedestals81 which form part-.of the main support for the machine. These pedestals8l are preferably formed with upper portions which provide for the readyassembly and disassembly of the supporting bearings and are, therefore,preferably made as removable hearing housing caps 88 secured to thelower portions of the pedestals in any suitable manner, as by throughbolts 89 extending into flanges 953 of the pedestals 8l. The bearings 86preferably are formed as double tapered roller bearings to provide forthe absorption of end thrust which may be transmitted thereto by therelatively stationary member of the machine. In this construction, as inthat shown in Fig. l, the end thrust of the machine is adapted to beneutralized by the electromagnetic arrangement such that under normaloperating conditions substantially no end thrust should be transmittedto the bearings which are arranged to support the stationary member ofthe machine.

The relatively stationary member of the machine is formed with a p-airof axially spaced end core members 9| and may be provided with one ormore intermediate core members, as shown at 92. These core members allare formed of magnetic material with substantially radial faces 93 onthe end members 9| and faces 94 on the intermediate member 92,respectively. The stationary core members are arranged to provide pairsof axially spaced radial faces on adjacent stationary core membersbetween each pair of which a core member of the main rotatable member isarranged.

When the capacity of the machine is such that it is desirable to providea plurality of pairs of axially spaced stationary core faces, the mainrotatable member of the machine is provided with a plurality of similarcore members 95 of magnetic material arranged one intermediate each pairof axially spaced radial faces of adjacent stationary core members.These rotatable core members 95 are formed with substantially radialfaces 96 on each side thereof which are axially spaced from adjacentstationary core member faces by relatively small air gaps, indicated at91. The rotatable core members 95 are rigidly mounted on a suitableshaft 98 and may be secured thereto in any suitable manner. Tofacilitate assembly and repairs, the shaft 98 is formed with shoulders99 against which the rotatable core members 95 are secured axially bynuts I 00 which threadedly engage the shaft 98, and keys |0| engagekeyways |02 in hubs |03 of the cores 95 and keyways in the shaft 98 to 9secure the ycores against .relative .rotational displacement on theshaft.

Each rotatable core member and its pair of ycooperating stationary-fcore members can be designed for a predetermined maximum capacity, andmachines of multiples of such standard capacity can be made byvassembling the .desired multiple Ynumber of 4sets of cores on asuitable shaft formed with stepped shoulders and .threaded portionsformounting the `sets Yof cores. .This construction provides for readydisassembly from either end for repairs of damaged coils or other partswithout special drawing tools or presses. In assembling the machine, therotatable core members 95 may be secured to the shaft 98 with thedesired spacing 0n each sidevof .the intermediate stationary core member92, `and Athe air gaps 91 may be adjusted to the desired width byvarying the spacingbetween adjacent stationary-core members.Thisadjustment may beobtained by securing together these stationary coremembers by housing members |04 fastened in axially adjustablerelationship by suitable means,

desirable that the energy which is `to be absorbed by the generation ofeddy currents in either or both `the Vstationary or rotatable-members'ofthe machine and transformed into -heat -be rdissipated as quickly aspossible to utilize the material in the machine -most efficiently and toprevent overheating ofthe machine. In this embodiment of my invention,the eddy currents vare 'adaptedto beigenerated nin-both the:rotatableand Vstationary members in the larger surfaces Vof both ofthese members, thereby utilizing-the material of these members tomaximum capacity.

Themagnetic excitation of the machine may be provided in any suitablemanner, Aas byelectromagnetic field exciting `windings mountedin themachine to provide a substantially torrie magnetic iield linking thestationary and rotatable core members. rI-he -material of the lcoremembers of the machine ismost-effectively utilized by providing forsubstantially uniform'magnetic density in the surfaces of the radialcore faces. This may be obtained in my improved construction byproviding a substantially 'circular field exciting winding recess ineach .of ythe stationary core members and arranging a field excitingwinding in these winding recesses which is adapted to `be electricallyenergized in any suitable manner. The substantially uniform saturationof the radial core faces is obtained by arranging the iield lexcitingwinding recess in a position so as to divide the stationarymember facesinto two substantially equal areas'radially spacedapartinsubstantiallythe samemanner as explained with reference to Figs.1 and 4. Magnetic iiux variations or pulsations link the facesof thestationary and'rotatablelmembers vby providing rteeth in these radialfaces `suchthat rotation of the rotatable core members `95 provides fluxvariations in the `radial faces 'of `lthe member spaced from the toothedface. The desired teeth are formed in 'the stationary core 'therotatable member.

Y1-0 members by providing a plurality of outwardly extending substantialradial slots |08 in the sta- .tionary core member faces. These slotsalsopreferabl-y are substantially equally angularly spaced apart, andthe number of these slots may be made such as to obtain the desired fluxdensity or saturation in the core material between the slots which formthe magnetic exciting teeth. -Since the radial slots |68 are relativelymuch further apart near the outer periphery of the core than at theinner portion, increased capacity and efciency may be obtained byproviding a :plurality of relatively short outwardly extendingsubstantially radial slots |09 arranged intermediate-.theslots |238 andspaced substantially equally angularly from each other and the slots|08. These additional slots preferably extend .from the outer peripheryof the core to a point inwardly where it provides for efficient magneticiiux saturation, usually to the outside of an exciting Winding recessHB. The material of the machine is adapted to be utilized still moreeffectively by providing a plurality of outwardly extendingsubstantially equally angularly spaced slots in the radial faces of therotatable core members 95, similar to slots 3| in Figs. 1 and 2, for thegeneration of eddy currents in the stationary core faces by magnetic.flux variations therein or rotation of the rotatable :core members,`but the number of these slots preferably 'is .considerably less thanthe slots in the stationary member, so that a larger amount of theradial -faces of the rotatable core members is Vavailable `for thegeneration of eddy currents therein than in the stationary core memberfaces, as

cooling of the rotatable core members can be more effectively obtainedthan cooling of the lstationary core members because ofthe rotation ofIn order to improve smooth operation of the machine, the slots in therotatable core members are different in number Afrom and axially spacedan uneven multiple'of the annular spacing of the stationary'core faceslots |08, such that not more than one of vthe rotatable member coreslots can at any time become aligned with a stationary core member slot|58.

The magnetic excitation of the machine may be obtained in any suitablemanner and is preferably provided by a field exciting winding whichincludes a plurality of exciting winding coils 'arranged in fieldexciting winding recesses in the stationary core members. Theenergization of the iield exciting winding may be varied in any desiredmanner to control the excitation and consequently the energy absorptionof the machine. For yfthe most effective use of the radial faces of vthestationary core members, the field exciting winding recesses are formedas explained with reference to Fig. 4 and may include uniform depthrecesses ||il as shown in Figs. 5 and 6 'or-variations as shown in Fig.1.

'byeddy currents by direct iiow `through these members. iand 6, this isobtained by supplying asuitable @cooling fluid, such as water, into thestationary .-'member of the machine'through a header system .inllllingconnecting pipesections |1|2Iar1d l1|3,it'o

In the construction shown in Figs. 5

. l1 which water is supplied through a flexible connection I4, such as arubber hosing, which is connected to a suitable source of cooling fluisupply. These connecting ypipe sections Il?. and ||3 are connected tonipples ||5 through Ls H5 and an X III, and the latter connecting Xprovides a connection of the headers to the flexible connection H4through a suitable regulating valve H8 which may be of the manual typeor of the electromagnetic type adapted to vary the flow of cooling fluidin accordance with the temperature of the cooling fluid which isexhausted from the machine similar to that of Fig. 1. This control ofthe amount of cooling fluid passing through the machine assures the mosteflicient utilization of cooling fluid so as to prevent overheating ofthe machine and also to prevent a wasteful ow of excess cooling uidthrough the machine.

The cooling uid is admitted into the interior lof the machine from thesupply nipples H and flows into radially extending cooling fluidpassages H9 in the intermediate stationary core member. These radiallyextending cooling fluid passages ||9 communicate with axially extendingcooling uid passages |2El, through which the cooling fluid flows intocooling fluid supply tubes |2| secured to the stationary member co-res.The cooling fluid is supplied to the rotatable member cores 95 from thetubes |2| by passing from these tubes into cooling fluid troughs |22lwhich extend between inner and outer annular lips, and the troughs |22communicate directly with a plurality of outwardly extendingsubstantially radial passages |23 spaced substantially equally angularlyaround the periphery of the rotatable member core and extending throughsubstantially the central axial parts of these members. The outwardlyextending cooling fluid passages |23 preferably are arranged equallyangularly between the slots and communicate with the air gaps betweenthe rotatable and stationary members through a plurality of angularlyoutwardly extending passages |24 on each side thereof, such .thatrotation of the rotatable member cores 95 causes cooling fluid to bepumped under centrifugal force through the passages |23 and to flowoutwardly through the passages |24 in an outward direction into contactwith the radial eddy current faces of the stationary member cores. Inthis manner, the cooling fluid is sprayed in a relatively thin film overthe entire surfaces of the stationary member cores and is also splashedback over the eddy current surfaces of the rotatable member cores. Inaddition, the cooling fluid lpasses over the outer surfaces of the eldexciting winding coils in recesses |l0 and thereby also removes the heatgenerated by the energizing current in these coils.

Rotation of the rotatable member cores imparts to the cooling fluid,which is pumped through the cooling uid passages in these cores, anoutwardly directed force which causes the cooling uid to pass radiallyoutwardly from the air gaps between the rotatable and stationary membercores into the space around the rotatable member core on the outside ofthe air gaps within the housings |04. 'Ihese housings form cooling fluidcollecting scrolls such that cooling fluid passing into these housingswill collect in the lower portion of the machine, from which it isadapted to be drained. The radially extending cooling uid passages |23may be most eifectively utilized as ydirect cooling channels byrestricting the open- 12 ings in the ends of these passages by theinsertion therein of plugsV |25 which are each formed with a restrictedorifice therethrough to limit vthe amount of cooling fluid which passesdirectly into the collecting housings l. The cooling fluid which passesout of the air gaps of the machine into the collecting troughs formedbythe housings |04 collects in the lower portion of these Yhousings and isadapted to be drained therefrom in any suitable manner, as in the mannershown in Fig. 1. Y l

In order to facilitate the manufacture of the stationary member cores,the cooling Vfluid passages i23are adapted to be Vdrilled completelythrough. the core members and the inner ends of these passages areadapted toV be closed olf by suitable threaded pipe plugs |26. In thisconstruction, the .intermediate stationary core member 92 is rotatablymounted about the rotatable member shaft 98 on suitable bearings, suchas journal bearings |2'l of suitable material which may be waterlubricated or require no lubrication, as a synthetic resin or suitablealloy bearing. When this type machine is utilized as a dynamometer, aweighing balance arm is adapted to be connected to the stationary memberthrough a lug |28, as in any conventional equipment of this type. Inaddition, in this .type machine, the rotation of the relativelystationary member is limited to a predetermined angular displacement bya suitable set of stops which may include a stop |29 Vsecured to the endbearing housing frame and a pair of spaced apart stops |30 mounted onthe pedestal 87.

This construction providesY an arrangement whereby cooling fluidisutilized to absorb the heat generated in the eddy current surfaces ofthe machine by direct contact with the eddy current sur#- faces of boththe' stationary and rotatable members of the machine and also by passageof the cooling fluid directly through the inductor core Amembers inwhich the eddy currents are generated and provides for high accuracy ofthe device as a dynamometer in addition to a high eiliciency andeffective utlization of the material of the machine. In addition, thesimplified cooling and bearing arrangements provide a Very practicalconstruction adapted to production standards whereby multiples of unitcapacity may easily be obtained by merely adding more sets of cores tothe main stationary and rotatable members.

While I have illustrated and described particular embodiments of myinvention, modifications which are within the spirit and scope of myinvention may occur to those skilled in the art. I desire it to beunderstood, therefore, that all such modifications are included in thescope of the claims annexed to and forming a part Aof thisspeciiication.

What I claim as newand desire to secure by Letters Patent of the UnitedStates is:

1. A dynamoelectric machine having a pair of main relatively rotatablemembers having cores of magnetic material spaced with radially extendingair gaps therebetween, means for magnetically exciting said relativelyrotatable core members, a plurality of outwardly extending slots in theair gap surfaces of one of said main members, a plurality of slots inthe air gap surfaces of the other of said main members different innumber from the slots in said one member and not an evenmul-tiplethereof, cooling means including an inwardly extending passagein one of said main members connected to a source of agentia coolingfluid supply and afpluralityIof-outwardly extending lpass-ages in theother of said lmain members arranged to be supplied with cooling fluidfrom said passagein said one fmember and communicating -with saidair-gaps 'for supplying cooling fluidinto said-air-gaps into `directcontact withsaid air gap surfaces of said main members for'cooling saidmembers, and meansfor draining cooling fluid Yfrom said machine.

'2. Akdynamoe'lectricmachine including a relatively stationary memberhaving two end and at least #one intermediate axially `spaced apartfcore members -of magnetic material formed with radial faces and aplurality of outwardly .extending teeth in the adjacentradialfacesthereof, both radial faces of the intermediate of .saidstationary core members b'eing'provided withs'aid teeth and formingactive magnetic Aexciting and eddy current faces, a rotatable memberfhaving a ycore member of magnetic material with radial faces arrangedvbetween each adjacent pair` lnf said-stationary core members, aplurality of outwardly lextending slots in each of said rotatable corelmember radial faces, means including a field exciting winding for'magnetically exciting said stationary and :rotatable members, outwardlyA"extending passages through said rotatable core members `with:communicating passages extendingtherefrorn tothe adjacent outer radialfaces o'f .said rotatable vcore members, and means for supplying.cooling fluid to said rotatable Ymember passages for iiowtherethroughinto contact with the faces lof said rotatable and stationary corememberslfor .cooling said members bydirect contact therewith and by flowthrough said rotatable memberpassages .and slots.

A3. 'A vdynamoelectric machine Vincluding a relatively .stationarymember having apair of core members of magnetic material and havingradial faces, a rotatable'member having a core of magnetic material withradial faces arranged between .said vstationary core members with an airgap between said stationary core member and the:adjacent rotatable-core.member radial faces, `one `of said members `.being formed with .aplurality-of Voutwardly extending teeth vin -the radial faces thereof, asubstantially circular winding recess ineach radialface of saidstationary member arranged for-dividing each of said stationary memberradial faces into two substantially .equal areas radially spaced apart,.means including .fa substantially circular field exciting windingarranged in said winding recess for magnetically exciting saidstationary .and rotatable members,

outwardly extending passages through said r.o

tatable member communicating with said Aair gaps, and means forsupplying cooling fluid to saidrotatable member passages for vflow'therethroughinto .said air gaps .into Contact with vthe faces of said.stationary and rotatable members for coolingsaid members by directcontact therewith.

4. A dynamoelectric machine including amain relatively stationary memberhaving too end and atleast one intermediate axially spaced core membersformed of ymagnetic material and having substantially radial facesproviding pairs of axially spaced substantially radial faces on'adjacent s'tationary core membera'bothradial faces o'f the'intermediateof said stationary core members being arranged and formingactivemagnetic exciting and .eddy current faces, a mainro'tatable memberhaving -a plurality of ,core members o'f .magnetic material .arrangedone intermediate each of Asaid pairs ofaxially.spacedradialfaces ofadjacent stationary fcore ymembers and having substantially radial facesadjacent .thereto With 'an .air `gap between said stationary core memberand the-adjacent rotatable core member radial faces, a plurality ofoutwardly 'extending slots in said faces of at least one of said .mainmembers, lmeans for magnetically exciting said stationary and rotatablecore members, and means including a housing extending from adjacentstationary core members over each of said rotatable core members andcommunicating with the outer peripheral endsof the air gaps for 'forminga unitary structure-of said-stationary core members.

5. A dynamoe'lectr'ic machine including Va relatively stationary mainmember having a pair of core members with radial faces and formed ofmagnetic material, a main rotatable member having a core of magneticmaterial with vradial faces arranged between said stationary coremembers with an air gap between said stationary core member 'faces andthe adjacent zrotatable core `member radial faceaone of said rmainmembers being formed with a plurality of outwardly extending teeth inthe radial faces thereof, means including afield exciting rwinding formagnetically exciting said stationary androtatable kcore Lmembers,outwardly extending passages through said rotatable member corecommunicating withsaid air gaps, la radially extending 'cooling fluid:passage through vthe interiorzof at least one of said stationary'member cores, and 'means for supplying cooling iluid through saidstationary core `member cooling fluid passage `into said rotatablemember passages for :dow into -saidair gapsinto contact'wi-th theffacesof said stationary and rotatable members for coolingsaid `membersby-direct contact `therewith and by flow through said rotatable member.

6. `A dynamoelectric machine including a relatively stationary memberhaving a pair of axiallywspaced apart core members with radial faces andformed of .magnetic material, a rotatable member having a core ofmagnetic material with radial faces arranged between said stationarycore members, a plurality of outwardly extending teeth in the adjacentinner radial faces of said stationary member, means including asubstantially r`circular eld exciting winding for magnetically excitingsaid stationary and yrotatable members arranged to divide each of theradial faces of said Vstationary member into two substantially equalradially spaced apart areas, means for supporting said stationary memberfor limited rotarymovement, means for rotatably supporting saidrotatable member, outwardly extending passages through .said rotatablemember with communicating passages extending therefrom to 4the adjacentouter radial faces of said rotatable member, and. means for supplyingcooling uid .to .said V`rotatable member passages for ow .therethrough.into contact .with the faces of said .rotatable and stationary membersfor cooling said members .by .direct contact therewith.

'7. A dynamoelectric machine including a relatively .stationary memberhaving two end and `at least one .intermediate axially spaced apart coremembers of magnetic material formed with substantially radial faces anda plurality of outwardly extending slots in the adjacent radialfaces'thereof,i.both radial faces of the intermediate ,of .said.stationary core members beingr provided `with .said .slots .and formingactive magnetic yexciting and eddy current faces, a rotatable memberhaving a ,plurality of core members of l magnetic material with radialfaces arranged between each adjacent axially spaced pair of saidstationary core members, means for magnetically exciting said stationaryand rotatable members, outwardly extending passages through saidrotatable core members with communicating passages extending therefromto the adjacent outer radial faces of said rotatable core members, andmeans including at least one inwardly extending passage in saidstationary member for supplying cooling uid to said rotatable membercooling fluid passages for fiow therethrough into contact with the facesof said rotatable and stationary core mem-bers for cooling said membersby direct contact therewith and by flow through said rotatable memberpassages.

8. A dynamoelectric machine including a relatively stationary memberhaving a plurality of axially spaced core members with radial faces andformed of magnetic material, a rotatable member having a plurality ofcore members of magnetic material with radial faces arranged betweensaid stationary core members, a plurality of outwardly extending slotsin the adjacent radial faces of said stationary member, means includinga substantially circular field exciting winding for magneticallyexciting said stationary and rotatable members arranged to divide eachof the radial faces of said stationary member into two substantiallyequal radially spaced apart areas, outwardly extending passages throughsaid rotatable member with communicating passages extendingtherefrom tothe adjacent outer radial faces of said rotatable member, and means forsupplying cooling iiuid to said rotatable member passages for flowtherethrough into contact with the faces of said rotatable andstationary members for cooling members by direct contact therewith.

9. A dynamoelectric machine including a relatively stationary memberhaving a plurality of axially spaced core members of magnetic materialhaving radial faces, a rotatable member having a core of magneticmaterial with radial faces arranged between said stationary core memberswith an air gap between said stationary core member and the adjacentrotatable core member radial faces, one of said members being formedwith a plurality of outwardly extending slots in the radial facesthereof, a substantially circular winding recess in each radial face ofsaid stationary member, means including a substantially circular eldexciting winding arranged in said winding recess for magneticallyexciting said stationary and rotatable members, outwardly extendingpassages through said rotatable member communicating with said air gaps,and means including substantially radially inwardly extending passagesthrough at least one of said stationary core members for supplyingcooling fluid to said rotatable member passages for flow therethroughinto said air gaps into contact with the faces of said stationary androtatable members for cooling said members by direct contact therewith.

10. A dynamoelectric machine including a relatively stationary mainmember having a plurality of axially spaced core members with radialfaces and formed of magnetic material, a rotatable main member having aplurality of similar core members of magnetic material with radial facesand arranged between said stationary core members with an air gapbetween said stationary core member faces and the adjacent rotatablecore member radial faces, at least one of said main members being formedwith a plurality of outwardly extending slots in the radial facesthereof, means for magnetically exciting said stationary and rotatablecore members, outwardly extending passages through said rotatable membercore each having a plurality of radially spaced openings communicatingwith said air gaps, at least one substantially radial cooling uidpassage through at least one of said stationary member cores, and meansfor supplying cooling fluid through said stationary member into saidrotatable member passages for ow into said air gaps into contact withthe faces of said stationary and rotatable members for cooling saidmembers by direct contact therewith and by flow through said rotatablemember.

11. A dynamoelectric machine including a relatively stationary memberhaving axially spaced end and intermediate core members, all of saidstationary core members being formed of magnetic material and havingradial faces providing pairs of axially spaced radial faces on adjacentstationary core members, a rotatable member having a core member ofmagnetic material arranged intermediate each of said pairs of axiallyspaced radial faces of adjacent stationary core members and havingradial faces adjacent thereto with an air gap between said stationarycore member and the adjacent rotatable core member radial faces, aplurality of outwardly extending substantially equally angularly spacedradial slots in said faces of at least one of said meme bers, means formagnetically exciting said stationary and rotatable core members,cooling uid passages extending outwardly through said rotatable coremembers having openings communicating with said air gaps, substantiallyradially inwardly extending cooling uid passages through at least one ofsaid stationary core members, and means for supplying cooling fluidthrough said stationary member cooling uid passages into said rotatablecore member cooling iiuid passages for flow therethrough into said airgaps into contact with the faces of said stationary and rotatable coremembers for cooling said members thereby and by ow through saidrotatable member.

12. A dynamoelectric machine including a relatively stationary memberhaving axially spaced end and intermediate core members, all of saidstationary core members being formed of magnetic material and havingradial faces providing pairs of axially spaced radial faces on adjacentstationary core members, a rotatable member having a core member ofmagnetic material arranged intermediate each of said pairs of axiallyspaced radial faces of adjacent stationary core members and havingradial faces adjacent thereto with an air gap between said static-narycore member and the adjacent rotatable core member radial faces, aplurality of outwardly extending substantially equally angularly spacedradial slots in said stationary member faces, means for magneticallyexciting said stationary and rotatable core members, a plurality ofsubstantially equally angularly spaced radially extending slots in eachradial face of said rotatable core members different in number from andangularly spaced an uneven multiple of the angular spacing of saidstationary core face slots, cooling iiuid passages extending outwardlythrough said rotatable core members having openings communicating withsaid air gaps, inwardly extending cooling fluid passages through atleast one of said stationary core members, means for supplying coolingud 17 through said stationary member cooling fluid passages into saidrotatable core member cooling uid passages for flow therethrough intosaid air gaps into contact with the faces of said stationary androtatable core members for cooling said members thereby and by flowthrough said rotatable member, and means including a housing secured tosaid stationary member and arranged over each of said rotatable coremembers and communicatlng with the outer peripheral ends of the air gapsbetween said rotatable and stationary core members for collecting anddraining cooling fluid exhausted from said air gaps.

13. A dynamoelectric machine including a relatively stationary memberhaving axially spaced end and intermediate core members, all of saidstationary core members being formed of magnetic material and havingradial faces providing pairs of axially spaced radial faces on adjacentstationary core members, a rotatable member having a core member ofmagnetic material arranged intermediate each of said pairs of axiallyspaced radial faces of adjacent stationary core members and havingradial faces adjacent thereto with an air gap between said stationarycore member and the adjacent rotatable core member radial faces, asubstantially circular field exciting winding recess in each radial faceof said stationary end core members adjacent one of said rotatable coremember faces arranged for dividing each of said stationary end memberradial faces into two substantially equal areas radially spaced apart,each intermediate stationary core member having a field exciting windingrecess in both faces with substantially circular inner and outerradially spaced sides and with a base extending angularly to the planeof the faces of said core member such that a section through saidwinding recesses provides substantially parallel bases with a wider sidenearer the outer periphery L" of the core for one recess and a widerside nearer the axis of the core for the other recess, said one recessbeing radially displaced nearer the outer periphery of the core and saidother recess being displaced nearer the axis of the core than saidwinding recesses in said end core members for providing a relativelylarge magnetic material section between said intermediate core memberrecesses, a plurality of substantially equally angun larly spacedoutwardly extending substantially radial slots extending on both sidesof each winding recess in said stationary core member faces, othersubstantially radial slots intermediate said first-mentioned slots insaid stationary member faces and extending from each winding recess tothe outer periphery of said cores, and means including a ileld excitingwinding arranged in each of said winding recesses and conforming ingeneral to the contours f each respective recess for magneticallyexciting said stationary and rotatable core members.

14. A dynamoelectric machine including a relatively stationary memberhaving axially spaced end and intermediate core members, all of saidstationary core members being formed of magnetic material and havingradial faces providing pairs of axially spaced radial faces on adjacentstationary core members, a rotatable member having a core member ofmagnetic material arranged intermediate each of said pairs of axiallyspaced radial faces of adjacent stationary core members and havingradial faces adjacent thereto with an air gap between said stationarycore member and the adjacent rotatable core member radial faces, asubstantially circular field exciting winding recess in each of saidstationary core member radial faces adjacent one of said rotatable coremember faces arranged for dividing each of said stationary member radialfaces into two substantially equal areas radially spaced apart, aplurality of outwardly extending substantially equally angularly spacedslots in said faces of at least one of said members, means including afield exciting winding arranged in each of said winding recesses formagnetically exciting said stationary and rotatable core members,cooling fluid passages extending outwardly through said rotatable coremembers having openings communicating with said air gaps, inwardlyextending cooling fluid passages through said stationary member, meansfor supplying and regulating the flow of cooling fluid through saidstationary member cooling fluid passages into said rotatable core membercooling fluid passages for flow therethrough into said air gaps intocontact with said faces of said stationary and rotatable core membersfor cooling said members thereby, means including a housing arrangedover each of said rotatable core members and communicating with theouter peripheral ends of the air gaps between said rotatable andstationary core members for collecting cooling fluid exhausted from saidair gaps, and means including a drain passage through the lower portionof said housing with a baille extending transversely across said housingover said opening for minimizing circulation of cooling iluid withinsaid housing and draining it therefrom.

15. A dynamoelectric machine including a relatively stationary memberhaving a pair of axially spaced end core members and an intermediatecore member, all of said stationary core members being formed ofmagnetic material and having radial faces providing pairs of axiallyspaced radial faces on adjacent stationary core members, a rotatablemember having a core member of magnetic material arranged intermediateeach of said pairs of axially spaced radial faces of adjacent stationarycore members and having radial faces adjacent thereto with an air gapbetween said stationary core member and the adjacent rotatable coremember radial faces, a substantially circular field exciting windingrecess in each radial face of4 said stationary end core members adjacentone of said rotatable core member faces arranged for dividing each ofsaid stationary end member radial faces into two substantially equalareas radially spaced apart, each intermediate stationary core memberhaving a field exciting winding recess in both faces with substantiallycircular inner and outer radially spaced sides and with a base extendingangularly to the plane of the faces of said core member such that asection through said winding recesses provides substantially parallelbases with a wider side nearer the outer periphery of the core for onerecess and a wider side nearer the axis of the core for the otherrecess, said one recess being radially displaced nearer the outerperiphery of the core and said other recess being displaced nearer theaxis of the core than said Winding recesses in said end core members forproviding a relatively large magnetic material section between saidintermediate core member recesses, a plurality of outwardly extendingsubstantially radial slots in said stationary member faces spacedangularly substantially equally and extending on both sides of eachwinding recess, other substantially radial slots intermediate saidfirst-mentioned slots in said stationary member 'meas-5i Y Y 19 .o faces'and 'extending from each Winding recess to the outer periphery vof saidcores, means including an insulated field "exciting Winding varranged in'a Waterproof nonmagnetic sheath in each of said Winding recesses andconforming in general to the contours of each respective recess formagnetically excitingsaid stationary androtatable core members, aplurality of substantially equally angularly spaced radially extendingslots in each radial face of saidrrotatable core members [diierent innumber from said stationary core face slots, cooling fluid passagesextending outwardly through said rotatable core members arrangedcircumferentially intermediate said rotatable core face slots and havingopenings communicating with said air gaps, means for restricting the.opening of said passages at the outer peripheral Vends thereof, inwardlyextending substantiallyY radial cooling uid passages through at leastone of said stationary core members, means for supplying and regulatingthe flow of c001- ing iluid through said stationary core member coolingfluid passages into said rotatable core member cooling iiuid passagesfor 110W therethrough into said air gaps into contact with the faces ofsaid stationary and rotatable core members for cooling said membersthereby and by flow through said rotatable member, means including ahousing secured to said stationary member and n REFERENCES CITED Thefollowing references are of record in the le of this patent: Y

UNITED STATES PATENTS 'Number Name Date 982,789 Bowie Jan. 31, 19111,650,594 Bing Nov. 29, 1927 2,068,820 Sarazin Jan, 26, 1937 2,110,663Gouldth'orpe Mar. 8, 1938 `v2,407,504 Martn Sept. 10, 1946 2,453,509Hugin Nov. 9, 1948 FOREIGN PA'IENTS Number Country Date 243,557GrermanyV May 13, 1910

